Chemistry 12 — U6 Practice Exam MCQ¶
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创建日期: 2026-03-22 最后更新: 2026-03-22
使用说明¶
- 题目数量：15 道选择题（Multiple Choice Questions）
- 来源：StudyForge — Quiz 11446-152507 (U6 Practice Exam)
- 答案位置：每题下方附 Answer
- 覆盖范围：Unit 6 — pH Calculations, Buffers & Titrations
- 成绩：100% | 15/15（Xin Peng, 2026-03-22）
Q1. Consider the following equilibrium for phenolphthalein:
HInd ⇌ H⁺ + Ind⁻
When phenolphthalein is added to 1.0 M NaOH, the colour of the resulting solution is
(A) colourless as [HInd] is greater than [Ind⁻] (B) pink as [HInd] is greater than [Ind⁻] (C) pink as [HInd] is less than [Ind⁻] (D) colourless as [HInd] is less than [Ind⁻]
Answer: (C)
Q2. Which of the following 0.10 M solutions will be yellow in the presence of the indicator chlorophenol red?
(A) K₂CO₃ (B) AlCl₃ (C) Na₃PO₄ (D) CaCl₂
Answer: (B)
Q3. The stoichiometric point of a titration is reached when 35.50 mL 0.40 M HBr is added to a 25.00 mL sample of LiOH. The original [LiOH] is
(A) 0.57 M (B) 0.024 M (C) 0.28 M (D) 0.014 M
Answer: (A)
Q4. What is the pH of a solution prepared by adding 0.50 mol KOH to 1.0 L of 0.30 M HNO₃?
(A) 0.70 (B) 0.20 (C) 13.80 (D) 13.30
Answer: (D)
Q5. A basic buffer solution can be prepared by mixing equal numbers of moles of
(A) NH₄Cl and HCl (B) NaCl and NaOH (C) NaCH₃COO and CH₃COOH (D) Na₂CO₃ and NaHCO₃
Answer: (D)
Q6. Identify the indicator that is blue in a solution when [H₃O⁺] = 2.5 × 10⁻⁶.
(A) bromcresol green (B) thymol blue (C) bromthymol blue (D) thymolphthalein
Answer: (A)
Q7. Which of the following, when dissolved in water, produces a basic solution?
(A) MgO (B) SO₃ (C) SO₂ (D) CO₂
Answer: (A)
Q8. Which of the following indicators would be yellow at pH 7 and blue at pH 10?
(A) thymol blue (B) bromcresol green (C) bromthymol blue (D) methyl violet
Answer: (A)
Q9. Which of the following standardized solutions should a chemist select when titrating a 25.00 mL sample of 0.1 M NH₃, using methyl red as an indicator?
(A) 6.00 M HNO₃ (B) 0.105 M NaOH (C) 0.114 M HCl (D) 0.100 M CH₃COOH
Answer: (C)
Q10. A student combines 0.25 mol of NaOH and 0.20 mol of HCl in water to make 2.0 litres of solution. The pH of this solution is
(A) 12.4 (B) 1.3 (C) 1.6 (D) 12.7
Answer: (A)
Q11. Consider the following equilibrium:
HF(aq) + H₂O(l) ⇌ H₃O⁺(aq) + F⁻(aq)
The above system will behave as a buffer when the [F⁻] is approximately equal to
(A) Ka (B) [HF] (C) [H₃O⁺] (D) [H₂O]
Answer: (B)
Q12. Consider the following equilibrium for the indicator bromthymol blue:
HInd ⇌ H⁺ + Ind⁻ (yellow ⇌ blue)
A solution of bromthymol blue is yellow. What should a student do to change the colour of the solution to blue?
(A) Add an acid to shift the equilibrium left. (B) Add a base to shift the equilibrium left. (C) Add an acid to shift the equilibrium right. (D) Add a base to shift the equilibrium right.
Answer: (D)
Q13. The pH range of 'acid rain' is often
(A) 7 to 9 (B) 6 to 8 (C) 10 to 12 (D) 3 to 6
Answer: (D)
Q14. Which of the following gases results in the formation of acid rain?
(A) H₂ (B) NH₃ (C) O₃ (D) SO₂
Answer: (D)
Q15. Consider the following data:
| SOLUTION | INITIAL pH | FINAL pH |
|---|---|---|
| 1 | 1.0 | 4.0 |
| 2 | 2.0 | 6.0 |
| 3 | 6.0 | 3.0 |
| 4 | 9.0 | 3.0 |
In which solution has the [H₃O⁺] increased 1000 times?
(A) 2 (B) 3 (C) 1 (D) 4
Answer: (B)